Abu al-Abbas as-Saffah was a descendant of Mohammed's family.
Abul Abbas led the Abbasid revolution that overthrew the Omyyads in
749.

He eliminated the corrupt power of the Omayyads in Damascus
and initiated the dynasty of the Abbasids. Abbas safeguarded his victory by
killing most of the surviving members of the Omyyad house.

The Omyyads had governed from Damascus, leaving Mecca only its
religious predominance. The Abbasids founded a new city, Baghdad,
from which to rule their territories. There remained only one province
which refused to recognize the Abbasids, that was Spain. There, one of
the few Omayyads to survive founded an independent state in 756.